A typical fan includes a cylindrical hub body with a rotatable blade assembly coupled thereto. The rotatable blade assembly includes a spider with a plurality of arms extending outwardly from a cylindrical central portion connected to the hub body and a plurality of rotatable blades attached to the spider arms. One end of a cylindrical rod, or driveshaft, is disposed within an axial bore through the hub and coupled to the hub body using a set screw or other connection device. A drive unit, such as an electric motor, is coupled to the other end of the driveshaft and operates to transfer power to the hub body in the form of torque by rotating the driveshaft. Due to the coupling of the driveshaft to the hub, and the hub to the blade assembly, rotation of the driveshaft imparts rotation to the hub body and the blades.
Fans are employed in a wide variety of applications and industries, but common design criteria related to fan efficiency and noise requirements, for example, may be employed in many such applications.